[Bill Baer]

If you have ever seen a TAD shaking the tires you would understand why no one tried a suspended car.(They some times shake hard enough to knock out the driver temporarly!)
The comments that Chris has offered are correct for TD/SC where consistency is king!
But if you study the comp eliminator dragsters they are interested in all out performance and don't use suspensions because of the weight they also use the smallest rear tire possible to reduce rotating weight and are willing to give up some consistency for all out performance.
Since their class are weight per CI they try to get to the class minimum which is several hundred pounds less that your typical 1800-2000# S/C dragster.